The present invention relates to a thin-film transistor using hydrogenated amorphous silicon (a-Si:H) and to a thin-film device such as a display panel of the active matrix type using the thin-film transistors. More specifically, the invention relates to a thin-film transistor that has large conductivity and large drivability (large mutual conductance), a large process margin and little defects due to shorts between electrodes, and to a thin-film device such as a display panel using the thin-film transistors.
Conventional thin-film transistors are formed on an insulating substrate, and are constituted by a gate electrode, a gate insulator, a semiconductor layer, a source electrode and a drain electrode, and in which a bias voltage is applied to the source, drain and gate electrodes during its operation to flow an electric current to the channel as disclosed in, for example, Japanese Patent Laid-Open No. 26861/1987.